Reputed crime boss James “Whitey” Bulger made his initial appearances in federal court in Boston less than a week after he was arrested at an apartment in Santa Monica, where authorities say he was living out of sight of law enforcement for nearly 16 years.

Bulger, 81, who once ran South Boston’s Winter Hill Gang and was wanted in connection with 19 murders and other crimes, was arrested without incident by FBI agents June 22 at an apartment in the 1000 block of Third Street in Santa Monica. The FBI’s most wanted fugitive following the death of Osama bin Laden, Bulger was taken into custody with the use of a ruse only hours after the FBI received a tip from the public.

Bulger’s longtime companion, Catherine Greig, was also arrested by FBI agents. Greig, who was not implicated in Bulger’s alleged crimes, was federally charged in 1997 for harboring a fugitive, according to the FBI.

“We followed every lead, we explored every possibility, and when those leads ran out we did not sit back and wait for the phone to ring,” said FBI Boston Special Agent in Charge Richard DesLauriers. “The result is we have captured one of the FBI’s Ten Most Wanted Fugitives, a man notorious in Boston and around the world for the very serious crimes he is alleged to have committed.”

Steven Martinez, FBI assistant director in charge in Los Angeles, said the anonymous tip came just days after a new public service announcement aimed at locating Bulger ran in 14 cities across the country. The campaign was directed at areas where Bulger was known to have ties but did not include Los Angeles, Martinez said.

The PSA, which was designed to draw attention to Greig, who fled with Bulger in 1995, focused on the 60-year-old’s physical appearance, habits, and personality traits and was directed at women who might come in contact with her.

The FBI was offering a $2 million reward for information leading to Bulger’s arrest but Martinez could not confirm if the tipster was eligible for the reward.

Authorities said Bulger and Greig were living under the names of Charles and Carole Gasko at their rent-controlled apartment in Santa Monica.

Following the arrest by the FBI, the Santa Monica Police Department was called to provide assistance in the search of the apartment. Inside the apartment, authorities found more than $800,000 in cash, about 30 firearms including pistols, rifles and shotguns, several types of knives and several types of false identification, Martinez said.

Asked by reporters how he believes it was possible for Bulger to remain hidden for so long in a popular area like Santa Monica, Martinez said, “I think it’s obvious that he had the means and the wherewithal to remain anonymous.” He noted that the FBI had been pursuing the suspect for a number of years, but “it’s the nature of fugitive work” that some arrests can take years.

Santa Monica police Sgt. Richard Lewis said police had no reason to believe that Bulger lived in the city and he was not surprised that the suspect could stay out of sight of police despite being in a high tourist area.

“For about 90 percent of the public, they have no interaction with law enforcement at all in their entire lives,” he said.

The FBI remained confident that they would ultimately locate Bulger, said Martinez, adding that they are pleased they could bring the case to this conclusion.

“For us it was a big deal,” he said of the arrest. “Anytime you can say that you can cross a fugitive off the most wanted list it’s something any agent aspires to, and we’re proud the L.A. division had a part in it.”